The invention relates to a stator structure of a motor, and in particular to a stator structure capable of providing function of attaining bias when the motor is started and preventing reduced rotational efficiency of the motor.
Conventionally, a conventional motor has a stator structure and a rotor. The stator structure includes a stator part, preferably made of silicon steel, formed on the periphery thereof with at least one coil wound therearound. There are several magnets disposed on the inside of the rotor corresponding to the stator part of the stator structure. When electrical current passes through the coil via the magnets disposed on the inside of the rotor, the stator portions excite magnetic forces to drive the rotor via a shaft rotating with respect to the stator structure, thereby performing the basic function of the motor.
In FIG. 1, a conventional stator structure 1 of a motor includes a stator part 10, a guide portion 12 and at least one coil 14. The stator part 10 is formed by several laminated metallic plates 100 and each of the metallic plate 100 includes a fixed portion 1000 and several magnetic-pole portions 1001, as shown in FIG. 2. The fixed portion 1000 has a through hole 1003 to receive a shaft (used for supporting the stator structure 1, but not shown in Figs.) therein. The magnetic-pole portions 1001 extend outwardly from the fixed portion 1000. The guide portion 12 is disposed on the stator part 10 and includes several guide ends 120. Each of the guide ends 120 are positioned in the gap of any two of the magnetic-pole portions 1001.
In order to attain bias function when the motor is started, the outer circumference 1002 of each magnetic-pole portion 1001 is designed to be formed by several circular arcs with different radii. In FIG. 2, for example, the outer circumference 1002 of the magnetic-pole portion 1001 is formed by two circular arcs having two different radii R1 and R2. In FIG. 3, for example, an outer circumference 1004 of the magnetic-pole portion 1001 is formed by two circular arcs having two different radii R3 and R4, and a difference exists between the radius R3 and R4. When electrical current passes through the coil 14 wound around the stator part 10, the circular arcs with different radii respectively generate an magnetic field with an individual direction. The difference in direction of the magnetic fields generates a magnetic factor along a tangent direction, thereby driving the motor to start. However, the magnetic force excited from the coil is not completely employed for the rotation of the motor, resulting in low rotation efficiency of the motor.
Additionally, if the gaps of any two magnetic-pole portions 1001 of the stator structure 1 are too large, particularly of the rotor (not shown in Figs.) during rotation, the magnetic lines of force are discontinuously divergent and the magnets of the rotor cannot immediately induce magnetic force as the magnets of the rotor correspond to the gaps of the magnetic-pole portions 1001, resulting in an abrupt stop of the rotating rotor. Based on the guide portion 12 disposed on the stator part 10 and the guide ends 120 thereof positioned in the gaps of the magnetic-pole portions 1001, however, as the magnetic lines of force generated by the excited stator part 10 pass through the gaps of the magnetic-pole portions 1001, the magnetic lines of force are convergent and the magnetic force can be continuously provided for the rotor, preventing the rotating rotor from stopping abruptly.
Further, referring to both FIG. 4 and FIG. 5, another stator structure 2 of conventional motor has a stator part 11 that is formed by several laminated metallic plates 110 and several guide portions 112. Each of the guide portions 112 is formed by several laminated guide bars. Each of the metallic plates 110 has a fixed portion 1100 and the guide bars 1104 are connected and extending from the fixed portion 1100. The fixed portion 1100 has a through hole 1003 to receive a shaft (used for supporting the stator structure 2, but not shown in Figs.) therein. Although the guide portions 112 of the laminated plate 110 can prevent the rotating rotor from stopping abruptly, the structure of the guide portions 112 of the laminated plate 110 will hinder the installation of coils (not shown) or reduce the number of the coils, i.e., a predetermined number of coils with respect to the same specification of stators cannot be employed on the stator structure 2, resulting in decreased availability thereof.